1. Field of the Invention
Embodiments of the present invention generally relate to optical mode conversion by nonlinear effects. More specifically, embodiments of the present invention relate to nonlinear mode conversion utilizing intermodal four-wave mixing to convert light between modes for complex applications.
2. Description of the Related Art
For the use of optical fibers that support more than a single mode, it is desirable for many applications to have some way of coupling/converting light from one mode to another mode. There are many known ways to accomplish such conversion of light based on a linear conversion process. Among these linear conversion methods include the use of traditional mode converters, such as long period gratings, phase plates or spatial light modulators with the fiber.
In a typical linear mode conversion process, light may be provided in the fundamental (LP01) mode. The light is then passed through a traditional mode converter to convert light to a different mode, e.g., LP02. When using a traditional linear mode converter, the converted light is usually generated at the same wavelength at the input light, and for many applications, this is either acceptable or desirable. However, in certain instances, the operation bandwidth of a given application could be increased by being able to have the converted light generated at a different wavelength than the original input light.
Four-wave mixing is an intermodulation phenomenon in non-linear optics, whereby interactions between two wavelengths produce two extra wavelengths in the signal. Normally, four-wave mixing is utilized with various wavelengths within the same mode. As such, utilizing of a four-wave mixing process to attain mode conversion would traditionally require a grating or other form of known modecoverter.
Thus, there is a need for a method of nonlinear mode conversion to open up a vast new application area, which may be further enhanced with signal processing such as wavelength conversion, parametric amplification, high speed switching, optical sampling, pulse compression, optical regeneration, or the like.